The 53-year-old, mildly retarded man began Friday with his regular walk around the popular park.

Then, about 11 a.m., a teenager rode up behind him on a bike, cursed him and stabbed him nearly a dozen times, twice in the back of the head.

Gibbs staggered a few blocks home and called his sister, who alerted police. He remained in serious condition late Friday, and his attacker had not been caught. Police have ruled out robbery.

"The man said some hateful things, stabbed him and left," said St. Petersburg police spokesman Bill Proffitt. "It could be a random act of violence."

Proffitt said Gibbs could have been recognized from his regular walks at the park. In a brief conversation before surgery, he told police he didn't know the teenager.

Gibbs' neighbor Becky Sackreiter, 66, couldn't understand why he would be targeted. She was even more shocked that witnesses didn't come forward.

"I can't imagine no one seeing something," Sackreiter said. "Or even when the poor guy was walking home and made it home that no one could see the blood all over him."

Gibbs has lived alone since his father died last year. His sister bought a house in the neighborhood and helps him, taking him shopping because he doesn't drive.

When her brother called, Carol Gibbs thought he'd cut himself cooking, she told Sackreiter. But then he said he needed to go to a hospital. Crying, Carol Gibbs asked Sackreiter to pray for her brother as she left the house for Bayfront Medical Center.

After visiting the hospital later in the day, Sackreiter said surgeons had repaired Gibbs' finger, which was sliced as he held up his hands to defend himself.

Gibbs said the attacker was a white man 16 to 18 years old, 5 feet 6 and 125 pounds who wore a gray or brown hooded sweater and shorts. He was riding a small, chrome-colored, BMX-style bicycle.

Neighbors said Gibbs likes to collect cans, visit the park and care for his tidy lawn. His blue-trimmed house in the 5900 block of 21st Avenue N is well kept. In the yard, a tree and azaleas bloom lavender and pink.

Gibbs has no criminal record, according to the Florida Department of Law Enforcement, and neighbor Michael Appugliese said he doesn't bother anyone.

"It's ridiculous," said Appugliese, 22, who lives across the street. "I just don't understand something like that."

People shared the same sense of disbelief at the park, which bustled Friday with its usual games of baseball, tennis and basketball. A block from an elementary school, it's home to the J.W. Cate Recreation Center.

"This park is pretty crowded all the time, so I wouldn't think that somebody would do that," said Lan-Anh Nguyen, 32, while her toddler played near the playground and swing set.

She and her friend Vivian Hoang, also 32, visit the park about once a week.

"We just have to be careful," said Hoang, holding her newborn son. "We take our kids here all the time. That's really scary."

Times researchers Will Gorham and Caryn Baird contributed to this report. Stephanie Garry can be reached at (727)892-2374 or sgarry@sptimes.com.